Effects of seed priming on yield, yield components, and concentration of mineral phosphorus under drought stress in Calendula officinalis L.

The use of organic materials and nano-fertilizers to control the release of nutrients could be an effective step towards achieving sustainable agriculture. Drought stress is the most important factor limiting the growth and yield of medicinal plants including marigold (Calendula officinalis L.). This experiment was conducted under field conditions in a factorial arrangement in a randomized complete block design with three replications (replication in place) in the Research Farm of the Urmia and Salmas Agricultural Research Center. The first factor was irrigation method at two levels including normal irrigation and irrigation cut in the beginning of flowering, and the second factor was priming treatments in seven levels including the seeds primed with nano fertilizers (iron oxide, zinc oxide and oxide with concentrations of two in thousands) and the seeds primed with organic material (humic acid, 72 mg/L, salicylic acid 2000 micromole and ascorbic acid 200ppm) and control. The results indicated that the priming of seeds with nano materials and priming with organic materials caused an increased plant height, number of capitol, fresh and dry weight of the plant, fresh and dry weight of root, grain yield, harvest index, essential oil percentage, and mineral phosphorus percentage as well as increased quantitative and qualitative yield of marigold, especially in drought stress conditions. Therefore, its application could be recommended for sustainable and organic agriculture.